|Does the Mediterranean killifish Aphanius fasciatus (Teleostei : Cyprinodontidae) fit the one-dimensional stepping-stone model of gene flow?|
Maltagliati, F. (1998). Does the Mediterranean killifish Aphanius fasciatus (Teleostei : Cyprinodontidae) fit the one-dimensional stepping-stone model of gene flow? Environ. Biol. Fish. 53: 385-392
In: Environmental Biology of Fishes. Junk: The Hague. ISSN 0378-1909, more
Allozymes; Brackishwater fish; Conservation; Differentiation; Differentiation; Fish; Genetic diversity; Geographical distribution; Marine; Pisces [WoRMS]; MED, Italy [Marine Regions]; Brackish water
Genetic variations; Population-structure; Brackish-water habitats; Population subdivision; Geographic pattern; Dispersal capabilities; Italian coasts; Waters; Geographic distance
Five samples (30 individuals each) of the Mediterranean cyprinodontid fish, Aphanius fasciatus, were analysed by allozyme electrophoresis for a study concerning genetic structure and gene flow among populations. Forty-three loci, twelve of which were polymorphic at P-0.99 level, were analysed. A. fasciatus showed low levels of genetic polymorphism with expected heterozygosity values ranging from 0.027 (SE = 0.013) to 0.064 (SE = 0.023). The modified Rogers' genetic distances ranged from 0.053 to 0.202. The observed pattern of genetic differentiation among populations, obtained by multidimensional scaling of the modified Rogers' genetic distances, was consistent with geographic distribution. Coancestry coefficient (theta = 0.302, SE = 0.045) indicated a very high degree of genetic subdivision among populations and the estimate of gene flow (the effective number of migrants per generation, Nm = 0.445), computed by Wrights method, showed very restricted gene flow among populations. The regression analysis carried out using log-transformed values of geographic distance against (M) over cap (pairwise values of Nm) gave a regression coefficient, b = -1.03, indicating that a restricted migration rate among populations can occur according to the one-dimensional stepping-stone model. The amount and modality of gene flow in A. fasciatus inferred from the results of the present study are consistent with the absence of dispersal stages and with the fragmented nature of brackish-water habitats along the coasts.